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Aug. 27, 1946. R, 'B, ,MMEL ' 2,406,377 ADJUSTABLE TIME LIMIT DEVI-CE Filed July 20, 1943 WITNESSES: ' 5% 7% r ' 2 Sheets-Sheet l . ‘ M ‘M ‘/ a“ “a? ' ‘ INVENTOR 5040/) ?lm/776A M2, BY ' ATTORNEY Aug- 27, 1946- R. B. IMMIEL . ADJUSTABLE TIME LIMIT_ DEVICE 7 2,406,377 Filed July 20, 1945 2 Sheets-Sheet 2 I 2 22 '3 z ‘ 24 22 I9 .1 WITNESSES: I if INVENTOR ’ EOJO?JT/mme? ' M ‘MM ‘ ’ BY I ' v M :3 Wmmi ATTORNEY Patented Aug. 27, I946 ‘UNITED STATES PATENT OFFICE Ralph E. Immel, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pitts burgh , Pa., a corporation of Pennsylvania Application July 20, 1943, Serial No. 495,467 3 Claims. (Cl. 175-372) 2 My invention relates to direct-current ener gized contactors, switches, relays and the like tactor Whose manufacture and assembly can be substantially completed regardless of the partic body from its supporting frame or permanent cir_ cuit connections. Another object in line with the foregoing is to permit a ready adjustment or change of the time limit by the user of the device, 1. e. outside the factory or after the device has been installed in its ultimate‘place of operation. While the invention involves using a selective plurality of short-circuited Winding elements, it after .1 is also among its objects to render the time-limit adjustment more accurate and de?nitely prede~ termined than heretofore obtainable. netically reluctant shims or netic circuit of the device and to adjust turn spring of the relay armature'relative to the ular, a de?nite dependence of the time limit on the selected windings regardless of their speci?c location along the magnetic forces so as them, is intended. delays. However, the time-limit devices of this type, as 25 Having these objects in mind, I propose accord ing to this invention, to arrange the magnetizing 7st etofore available, offer a rather limited or no coils of time-limit devices so that they surround appreciable range of adjustability; that is, the the appertaining magnet core with sumcient play devices are usually manufactured for a given time to form" a peripheral interstice, and to provide limit and, once in the ?nished state, do not'permit changing the limit to an appreciable extent, or 30 require for this purpose an extensive disassem bly or reconstruction of the magnetic structure. In one of the known time-limit relays, a plu rality of copper discs are placed on the magnet ‘core of the relay, and the time limit is adjusted of the inserted Winding byselecting the number of discs thus employed. 35 elements relative tothe core and determined only The adjustment has to be made during the course by the total cross section of the windings, or, if of manufacture and cannot be changed Without the elements are substantially alike, only on their severing the permanently interconnected parts of selected number. the magnetic structure from one another and 40 According to another feature of my invention, from their common base or support once the relay the magnet core and armature of a time-limit in been assembled in the factory; and it is also device as relferredto above are attached to a diilicult to obtain accurate and de?nitely prede magnetic supporting structure so that the arma termined time constants since the delay charac ture is readily removable, While a selective plu .teristic of this relay depends not only on the rality of annular ' ‘ number or total cross section of the copper discs, but also on their location relative to the magnet ture when the latter is removed. core and armature. In still another aspect, the invention provides It is an object of my invention to provide an an electromagnetic time-limit device with a fixed elec romagnetic time-limit device Which aiTords adjustment and change of the time limit with considerably greater ease than afforded by the known devices of this type. I More speci?cally, in this aspect, the invention aims at providing a type of electromagnetic con- 55 52,406,397 3 interfere with the insertion or removal of the annular elements. The invention is represented by the embodi ments shown in the drawings, in which: Figure 1 is a top view of a timing relay. Fig. 2 is a part-sectional side elevation. Fig. 3 is a front elevation of the same relay, while Fig. ashows a diagram of time delays in de pendence upon the selected number of short— circuited winding elements, and; the illustrated position, the contact member H is moved away from the stationary contacts [5 and Hi. When the armature is attracted by the magnet core 2 against the force of spring in, the contact member l4 moves against the stationary contacts and establishes an electric connection between terminals l1 and, I8 through contact members l5, Ill and US. As apparent from Figs. 1, 2 and 3, the armature 6 and all other parts assembled therewith can be readily removed from the supporting structure Figs. 5 through 7 are side elevations of three other embodiments distinguished by different de I and its appertaining parts by pulling the cross bar ll out of engagement with the openings (3 of the abutment plate ‘I and then moving the signs and arrangements of a magnetically re— cross bar and the armature B away from the mag 15 net core 2. In the opposite manner, the assem luctant shim element. bly can be reinserted into the relay. When the Referring to Figs. 1, 2 and 3, numeral I denotes a magnetizable supporting structure consisting, armature assembly is removed, the front surface for instance, of an angular piece of iron. of the core structure is readily accessible. An A magnetizing direct current coil is is mount elongated cylindrical magnet core 2 is mounted on the support I and carries at one end a shim 20 ed on a supporting structure I so as to surround 3 and a pole piece 4, both attached to the core 2 by means of a screw ‘5. The shim consists of a material of high magnetic reluctance, for in stance of a disc made of brass. The screw 5 may also consist of brass or the like reluctant ma terial. It should be noted that the diameter of the shim 3 and of the pole piece 4 are equal to the diameter of the core member 2 so that the entire core assembly has a straight cylindrical shape over the entire longitudinal extent of the the core member 2 with sufficient play to form a cylindric interstice between the core and coil. Two bolts 20 and 2! serve for fastening the sup porting structure I to a suitable base. Referring more particularly to Fig. 2, it will be seen that the just-mentioned interstice between the magnet core and the magnetizing coil con tains a plurality of annular elements 22. In the illustrated embodiments, these elements consist of slugs or rings of a material of relatively good electric conductivity so that each of them forms a short circuited current path around the magnet A magnetic armature 6 has its upper edge core assembly of elements 2, 3 and 4. The ele placed against the support I and is held in posi ments 22 may consist of copper rings although tion by means of an abutment plate 1 which other metals, such as iron, are also applicable. is ?rmly attached to the structure I. The upper The elements 22 are so dimensioned that they edge of the armature 6 contacting the structure have substantially the same size and can easily I is cut in an acute angle in order to permit be slipped on or off the magnet core when the the armature 3 rotational movements about the armature assembly is removed from the station fulcrum formed by the armature edge. A brack et member 9 is ?rmly secured to the armature 6, 40 ary relay structure. The electric resistance of the short circuited the lower end of this bracket, in the illustrated current path, assuming that the same material position, rests against a stationary abutment is employed for all elements 22, depends on the formed by a metal piece 8 which is mounted on the supporting structure I. This abutment piece 45 total cross section of the elements placed between the magnet core and the magnetizig coil. This limits the motion of the armature 6 in the direc total resistance and cross section can be adjusted tion away from the magnet core 2 and as illus by changing the number of elements 22. That trated, may contain a screw for adjusting the is, in order to increase the time constant of the inactive position of the armature. A bolt 26 has its lower end journalled to the 50 device the maximum number of elements 22, i. e. bracket member 9 and carries a helical spring six elements in the illustrated embodiment, are l0 whose lower end rests against a nut 21 engag to be inserted into the cylindrical interstice. For ing the bolt 26, while the upper end of the spring obtaining a lower time constant, the number of assembly. l0 abuts against the bracket member 9. The bolt elements 22 is reduced, the minimum retardation of relay action being obtained when all elements formed by the abutment plate 1. The two ends 55 22 are removed from the interstice. The ele 26 carries a cross bar H which bridges a recess of the cross bar are bent away at right angles and form lugs l2 which engage corresponding ments may have holes such as shown at 28 in ‘Fig. 2 or may be otherwise designed to facilitate openings l3 of the abutment plate ‘I. their removal. Due to the above-described possibility of re When the relay is in assembled condition as represented by Figs. 1, 2 and 3, the spring I0 60 moving the armature assembly and by virtue of is under compression and hence pulls the cross bar ll against the abutment plate 1 thereby se curing the lugs l2 in their engagement with the openings l3 while holding the armature 6 and the bracket 9 in the position shown in Fig. 2, in which the bracket member 9 rests against the abutment member 8. In this condition, the com pressed spring [0 biases the armature 6 away from the core 2. A contact member [4 carrying two contact pieces of silver is attached to the armature as sembly and cooperates with two stationary con tacts l5 and I6 which are ?rmly connected with the supporting structure I and are in electric con the fact that the space for receiving the short circuited winding elements 22 is open towards the armature and not obstructed by any part like the shim 3 and the pole piece 4, the relay can easily be adjusted to seven different time delays. Since the time constant, though to a lesser de gree, is also dependent on the adjustment force of the spring ID, the relay permits also an ad justment of its time constant to values interme diate those obtained by the above-mentioned se lection in the number of the winding elements 22. In other words, the adjusting nut 21 of spring l0 affords a vernier adjustment of intermediate time delay values. tact with terminals l1 and I8, respectively. In 75 2,406,377 Due to the fact that all short circuiting wind ing elements 22 lie within the range of the mag net core surrounded by the magnetizing coil IS, the location of the individual elements 22 along the core 2 has no noticeable e?ect on the time limit. Thus, even if only one element 22 is in serted into the relay, the time limit remains the 6 "constructions are so designed that they do not possibility and ease of con trolling the time constant by inserting a selected number of the short circuiting winding elements. While I have shown and described a limited number of modi?cations within the scope of my same whether the element lies next to the sup invention, it will be apparent from the foregoing porting structure I, or close to the armature, or to those skilled in the art that other embodiments in some intermediate position. 10 may be devised without departing from the prin The time delay curves shown in Fig. 4 are based ciples and teaching of this disclosure. Therefore, on test results obtained with a I wish this speci?cation to be considered as illus trative and not in a limiting sense. I claim as my invention: indicates the number of elements 22 inserted into 1. An electromagnetic time-limit device, c0m~ the coil while the ordinate values denote the time 15 prising a magnetic ?eld structure having a core, delays in seconds. The results were obtained by energizing the magnetizing core of the relay and an armature pivotally linked to said structure and then interrupting the energizing current. being biased away from one end of said core to be time elapsing attracted thereby when core is magnetized, a 20 magnetizing coil surrounding said core with will cient spacing to form an interstice around and cates the delays obtained with a relatively low along said core for the reception of short-circuit contact pressure, i. e. a corresponding adjustment of the relay spring 10, while curve D refers to the same relay with the spring l0 adjusted for a higher contact pressure. In both cases, the 25 period of delay was de?nitely determined by the number of winding elements 22. The two curves indicate that any period of delay between the 2. An electromagnetic time-limit device, com 30 prising a magnetic frame structure, an elongated core having one end attached to said structure tially the same results are obtained with differ ent shim arrangements. For instance, Fig. 5 shows a similar relay in which a shim of high magnetic reluctance, denoted by 23, is attached by the armature 6 and hence removable from i the stationary relay structure together with the armature assembly. According to the embodiment represented by Fig. 6, a shim 25 inserted between ' g 45 to be insertable and remov able from the side of said free end when said as sembly is removed from said structure, whereby the time-limit of the device is adjustable by a body of the magnet core 2 and is fastened by riveting the end 2! of the core. Similar to the corresponding selection of the inserted element. 3. An electromagnetic time-limit 50 prising a magnetic frame structure, an elongated 55 netizable supporting structure I. In this case, the shim 29 remams permanently attached to the relay is adjusted by elements, a plurality of short-circuiting cy lindrical ring elements the time limit of the device by a corresponding selection of said elements, said elements having a radial width nearly equal to that of said interstice. RALPH B. IMIMEL.